Mali is politically unstable and therefore lawlessness is wide spread. Since June 2012, Mali has been hit by a political crisis and a civil war, which has split the country into two parts: the north having proclaimed independence as "Azawad" in April 2012, yet the secular ethnic Tuareg movements which had control of the North were betrayed by their Islamist allies, who now have control of the Region. whilst the south experiences a military junta. Travelling in Timbuktu and Gao provinces are particularly extremely dangerous, and as of July 2012, the Islamist rebel groups have ordered all shrines which are considered to involve idolatry to be destroyed. The U.S., Canada, Norway and UK travel advisories have since continued to advise against all travel to Mali at this time.
The train between Bamako and Kayes is notorious for theft: if taking the train, you should exercise extreme caution, carry a pocket flashlight, and keep your belongings with you and valuables directly on your person at all times.
You also have a good chance of encountering the police. They are generally mostly concerned with directing traffic and fining people for improper papers, so you have little to fear from them, but always at least carry a copy of your passport and visa and preferably the original if keep it secure.
Carrying only a driving license is not sufficient and might lead to a ride to the police office unless you bribe your way out. Notice that the police in Bamako often stop taxis, although this can be somewhat avoided by never putting more than four passengers in the car and by taking only "official" cabs the ones with the red plates only: in Bamako, a car with white plates is not an official taxi even if it has a taxi sign on top, regardless of what the driver may tell you.
The northeast half of Mali everything north and east of Mopti Province is simply not safe for travel, as the murky alliance of Al Qaeda and Tuareg rebel groups have been targeting foreigners for kidnappings. Unfortunately, in late 2011, these kidnappings have occurred in other parts of the country as well including the capital, and tourist-kidnapping by terrorists is a real concern.
French is the official language, but Bambara or Bamanakan in the language itself, along with numerous other African languages Peulh/Fula, Dogon, and Tamashek, the language of the Tuareg people, are spoken by 80% of the population. Few people speak French outside bigger towns, and even Bambara gets rare in some regions. Very few people speak English.
food and water
Stay away from dirty food and water. The rule "cook it peel it or forget it" should be followed. Also water should only be drunk out of sealed bottles or after it is sterilized through boiling or chemical utensils. The food is another issue. It's sometimes difficult to know if it's cooked long enough. Also the, to Westerners, unusual spices are sometimes the cause for sickness, especially diarrhea. Also expect little stones or bits of grit in the meal, especially the local couscous this doesn't mean it's unsafe though, as it has been cooked long and thoroughly. For the traveler the main danger is diarrhea. For mild diarrhea you should be sure to get lots of rest, drink lots of clean water and eat soft plain foods. If the diarrhea is severe or lasts several days, be prepared to take antibiotics. During the illness the body will lose a lot of water and salt. Coca Cola sugar and water and pretzel sticks salt are available everywhere and do a good job of getting travelers back to full strength. There are also instant powders that have the necessary glucose and salts available to purchase.
Mali is highly endemic for malaria, including s. falciparum malaria, the most acute variety. All travelers should plan to take a malaria prophylaxis throughout their time in Mali mephloquine and Malarone are the most common. The other main precautions are to use insect repellent in the evenings and to sleep under a mosquito net in all but the fancy, sealed, air-conditioned hotels. This will significantly lower your exposure to malaria as the mosquitos that carry the parasite are only active at night, but you would want to take these precautions even without the risk of malaria simply to avoid being covered in itchy mosquito bites! You will almost never see or be bothered by mosquitos during the day.
Although it is rarely enforced, you are technically required to have an international vaccination card showing immunization against yellow fever. It is also recommended to get Hepatitis A, Hepatitis B, typhoid, and meningitis vaccinations. You may also consider getting a polio vaccination due to the recent outbreak of polio in Northern Nigeria that has spread around the region.